1. Field of the Invention
The present invention relates to a multi-joint synchronous rotary axle structure, and more particularly to a rotary axle structure which can be mounted to two opposing foldable apparatuses for synchronous rotation and operation and has a more compact structure.
2. Description of the Prior Art
Nowadays, an electronic apparatus usually comprises a base as a system end and an upper cover as a display. The base and the upper cover are connected through a pivotal device. The upper cover can be opened upward to be in a use state with the pivotal device as the axle of operation, or the upper cover can be closed to the upper surface of the base to be in a closed state. The pivotal device is as the axle of the electronic apparatus, so the design of the structure must consider whether the operation relative to the base is smooth or not. When the upper cover is opened to a desired angle (for example, the screen of the notebook is opened to 135 degrees), the pivotal device must have enough support force to position the screen at the operation angle.
In general, the pivotal device comprises a connection member having a spindle and another connection member having a spindle sleeve. One connection member is mounted to the upper cover, and the other connection member is mounted to the base. The spindle and the spindle sleeve are connected with each other. To consider the support strength and the smoothness of operation, the two connection members having the spindle and the spindle sleeve are disposed at two opposing edges of the upper cover and the base of the electronic apparatus (such as a notebook).
This conventional pivotal device is arranged in the form of one set. When the upper cover of the electronic apparatus is opened, the coordination of two pivotal devices is not perfect because the two pivotal devices don't have the same spindle when being turned. Besides, the rotation degree of the two pivotal devices is also limited, so the electronic apparatus cannot be opened or closed smoothly.
Due to the functional limit of the aforesaid pivotal device and the demand for a larger angle of turning, a pivotal device not having the same spindle is developed and mounted between the upper cover and the base of the electronic apparatus. The coordination of the two spindles of the pivotal device cannot be controlled so the electronic apparatus cannot be closed or opened accurately and smoothly and the demand for a light operation cannot be achieved.
In order to improve the aforesaid shortcomings, a prior invention is developed as shown in FIG. 1 and FIG. 2. This device comprises at least one driving joint assembly 1 and at least one driven joint assembly 2. The driving joint assembly 1 comprises two opposing first and second joint plates 11, 12 and a middle link plate assembly 13 between the first and second joint plates 11, 12. The two opposing first and second joint plates 11, 12 have synchronous actuating portion 111, 121 at respective inner ends thereof. The middle link plate assembly 13 has two connecting actuating portions at the two ends thereof to mate with the synchronous actuating portions 111, 121 of the first joint plate 11 and the second joint plate 12. The driven joint assembly 2 is disposed between the first and second joint plates 11, 12 of the driving joint assembly 1. The driven joint assembly 2 comprises at least two driven plates 20, 21 which have synchronous actuating portions at respective inner ends thereof to mate with each other. The inner ends of the opposing joint plates 11, 12 correspond to the outer ends of the driven plates 20, 21 and are connected with axle pins 3. The outer ends of each middle link plate of the middle link plate assembly 13 correspond to the inner ends of the driven plates 20, 21 and are connected with axle pins. Besides, the outer ends of the opposing joint plates 11, 12 have insertion end heads 110, 120 for connecting with a foldable object 4 easily. Furthermore, the driving joint assembly 1 and the driven joint assembly 2 are arranged side by side, and the middle link plate assembly 13 between the opposing joint plates 11, 21 and the driven joint assembly 2 are connected through the axle pins to form a multi-joint synchronous rotary axle structure. Each joint plate of the driving joint assembly can be rotated freely through multiple rotation centers.
However, the aforesaid multi-joint synchronous rotary axle structure is composed of a plurality of toothed plates to achieve better transmission and the required torsion to support the turning angle. Because the parts are too many, the quality of the product can't be controlled easily. It is difficult to control the tightness of the plates. Sometimes, the lubricant may leak out. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.